1. Field of the Invention
The present invention relates to furnaces for the firing of ceramic objects and articles, and more particularly to a tunnel kiln for the firing of sanitary ceramic articles which are moved through the tunnel kiln on a series of railcars.
2. Description of the Prior Art
Firing furnaces in the form of tunnel kilns are not new, as reflected by the prior art in this field. However, prior art tunnel kilns are constructed in situ by erecting a gallery-type structure from furnace brick. Such a tunnel kiln may be reinforced by means of pilons, using traction anchors to hold the gallery walls. These prior art tunnel kilns are heated with either natural gas, or fossil fuel, or electrically. The heat may be introduced either directly or indirectly. In the case of direct heating, the burners or burner elements are arranged in the furnace cavity itself, in the case of indirect heating the kiln is equipped with special combustion chambers arranged in muffles.
These prior art tunnel kilns have several shortcomings and disadvantages. Among them are their elevated cost of initial construction, involving the use of refractory brick and requiring the work of highly skilled furnace bricklayers. In actual use, these tunnel kilns present various problems in connection with inspection and servicing, due to poor accessibility.